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Thread: Runs Rough - Real Rough?

  1. #1

    Runs Rough - Real Rough?

    My 2009 F650GS Twin sat idle for 30 months and now getting it back on the road. Started right up but was hard to keep running if I let rpms drop below 4000 rpm. Out on the road it shifts and accelerates fine - as long as I keep it above 4000 rpm - otherwise it just stalls out if there is any load on it below 4000 rpm. When I let it warm up in my driveway I can get it down to about 1500rpm without stalling - but I need to constantly jerk the throttle if it starts to die. It does not run smooth at any rpm - very twitchy. The cat gets very hot when not moving - cherry red - say over 1000 degrees - seems to be getting too much fuel and/or too little air.

    Here is what I have done - checked:
    Gas - drained every bit out of the tank and put in fresh gas with additive. Since it runs at high speed on freeway I have ruled out fuel pump issues or delivery as being a problem.
    Injectors - I pulled the injectors while attached to the fuel header and both spray a strong equal pattern on cardboard.
    Throttle Plate Movement - Twisting the throttle both plates open just fine - and close fully at rest.
    Air Filter - Bike has 3500 miles on it - filter looks like new.
    Idle Hoses (under airbox going to carb) - Not kinked - no reason to think they can not pass air.
    O2 Sensor - Don't like the look of this on my GS911 output (see attached file) and will eventually replace it, but running on open-circuit (disconnected) made no difference - still runs rough and hard to keep running.
    Throttle Positioning Sensor - Tried to calibrate this with GS911 - not sure if I was successful. GS911 output (see file) seems to show that this is not responding as I thought it would. Started the test at 9 (off) and finished at 4 (off) but in between (1500-6000 rpm) the reading does not seem to vary much as if it was more stuck than responsive - I think something is awry here - don't know what?
    Idle Valve Position - Tried to calibrate with GS911. GS911 output (see file) seem to show as if this is not responding as much as I thought it would. Started test at 140 (0 rpm) and ended at 110 (0 rpm) with the readings staying in the 40 to 60 range regardless of the rpm. Something may be awry here - don't know what?
    Ignition - Have not checked plugs, coils, or any ignition electrical matters. Guess this should be on my todo list.

    Comments? Suggestions?
    Attached Files Attached Files

  2. #2
    Fortis Fortuna Adiuvat Omega Man's Avatar
    Join Date
    Jan 2010
    I would check the battery condition and voltage. I would check for a mouse or critter nest in the air-box area. If these check out I would put a 20oz bottle of Techron in it, fill it with gas as ride it and see what changes.
    BTW, how is the tire pressure?
    "You can do good or you can do well. Sooner or later they make you choose." MI5
    Mod Squad
    2009 F800GS 1994 TW200

  3. #3
    Quote Originally Posted by Omega Man View Post
    I would check the ... and see what changes.
    FYI - Did all that and nothing changed. Thanks for the input.

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